GEOGRAPHICAL RANGE. 167 



The least prolific of these provinces contains 22 species, 

 or between Jth and ^th of the total number of species, and the 

 most prolific between ^d and Jth of this same number. In 

 each of these provinces, it is remarkable that the peculiar 

 species are very nearly two thirds of the whole of its inha- 

 bitants. These facts, I think, show that the above provinces 

 are natural divisions of the world, as far as their Cirripedial 

 inhabitants are concerned. 



As Cirripedes belong to the great class of Crustacea, 

 and as the distribution of the latter has lately been fully 

 discussed by Mr. Dana, it may be worth while briefly to 

 compare my results with his ; more especially as they are 

 so very different. I should premise, as perhaps accounting 

 to a certain extent for this difference, that, owing to the 

 wide range of many species, and the almost universal 

 extension of the same genera, my provinces are founded merely 

 on a certain proportion of the species, namely, two thirds, 

 being peculiar or confined to a region of considerable 

 dimensions : whereas, in the case of ordinary Crustaceans, 

 the greater number of the species are distinct even in the 

 sub-provinces, and the provinces are founded mainly on 

 generic differences. Mr. Dana divides the surface of the 

 globe into three great sections, or provinces, the Africo- 

 Uuropcean, the extent of which is shown by its title ; the 

 Occidental, which includes both the east and west coast of 

 both Americas ; and the Oriental, including the Indian and 

 Pacific Oceans, with the East Indian Archipelago, and 

 Australia. Thus Mr. Dana entirely separates the Eastern 

 shores of North America from Europe ; whereas, as far as 

 their Cirripedial inhabitants are concerned, they are most 

 intimately allied, and form my first or North Atlantic pro- 

 vince ; and to this, as I have shown, even the West Indies, 

 the coast of Brazil, and equatorial West Africa might have 

 been added. It follows, from this similarity in the Cirri- 

 pedes on the two sides of the Atlantic, and from their dis- 

 similarity with those on the shores of the Pacific, that the 

 east and west coasts of the two Americas form two quite dis- 

 tinct Cirripedial provinces; though, in the northern half, some 

 connection is shown by a few representative species : on the 

 other hand, Mr. Dana unites both sides of the whole American 



